A variety of subcutaneously implantable access ports have been utilized by physicians to deliver fluids to, or withdraw fluids from, the bloodstream or other subcutaneous cavities inside a patient. Such vascular access ports generally include a needle-impenetrable housing enclosing a fluid reservoir that is sealed by a needle penetrable septum. The access port also includes a port stem that projects from the housing and has a fluid passageway that communicates with the fluid reservoir. The port stem can be used to couple a catheter to the housing.
Typically, an access port may be attached to a catheter (e.g., via the port stem) after the catheter has been inserted within a subject. The access port is then implanted into an appropriate region of the subject's body so that the distal end of the catheter is disposed at a predetermined location where a therapeutic agent is to be delivered from the access port. Once the vascular access port is implanted, a needle attached to a syringe can selectively access the reservoir of the access port by penetrating the subject's skin overlaying the access port and enter the septum of the access port. The needle and syringe can then deliver fluids (including fluids containing medication or other therapeutics) to the target site. The fluids travel through the reservoir, port stem, and catheter, and are released from the distal end of the catheter. Alternatively, a syringe can be used to aspirate and withdraw bodily fluids from the region near the distal end of the catheter.
Fluid (e.g., medication) may be dispensed from the fluid reservoir of the access port by means of a non-coring needle, inserted through the penetrable septum. For example, this fluid may be applied from the distal end of the catheter to an entry point into the venous system of the body of the patient. Blood may also be withdrawn (e.g., for sampling) from the body of the patient through an access port by applying negative pressure in the fluid cavity, drawing blood through the catheter, into the fluid cavity, and then out of the body of the patient through the needle. To prevent clotting, the withdrawal route may be flushed with a saline solution or heparin using a non-coring needle injected into the access port in the same manner as if a medication were being infused. Both intermittent and continual injections of medication may be dispensed by the access port. Continual access may involve the use of a non-coring needle attached to an ambulatory-type pump or gravity feed bag suspended above the patient. The ambulatory-type pump or the gravity feed bag continually delivers the medication or fluid through the needle to the fluid cavity in the access port and from there through the catheter to the entry point into the venous system.
Examples of access ports are described in U.S. Pat. No. 4,772,270, titled “INSEPARABLE PORT/CATHETER TUBE ASSEMBLY AND METHODS” issued to Wiita et al., dated Sep. 20, 1988; U.S. Pat. No. 4,963,133, titled “CATHETER ATTACHMENT SYSTEM” issued to Whipple, dated Oct. 16, 1990; U.S. Pat. No. 5,045,060, titled “IMPLANTABLE INFUSION DEVICE” issued to Melsky et al., dated Sep. 3, 1991; U.S. Pat. No. 5,129,891, titled “CATHETER ATTACHMENT DEVICE” issued to Young, dated Jul. 14, 1992; U.S. Pat. No. 5,137,529, titled “INJECTION PORT” issued to Watson et al., dated Aug. 11, 1992; U.S. Pat. No. 5,312,337, titled “CATHETER ATTACHMENT DEVICE” issued to Flaherty et al., dated May 17, 1994; U.S. Pat. No. 5,360,407, titled “IMPLANTABLE DUAL ACCESS PORT WITH TACTILE RIDGE FOR POSITION SENSING” issued to Leonard, dated Nov. 1, 1994; U.S. Pat. No. 5,399,168, titled “IMPLANTABLE PLURAL FLUID CAVITY PORT” issued to Wadsworth, Jr. et al., dated Mar. 21, 1995; U.S. Pat. No. 5,833,654, titled “LONGITUDINALLY ALIGNED DUAL RESERVOIR ACCESS PORT” issued to Powers et al., dated Nov. 10, 1998; U.S. Pat. No. 6,113,572, titled “MULTIPLE-TYPE CATHETER CONNECTION SYSTEMS” issued to Gailey et al., dated Sep. 5, 2000; U.S. Pat. No. 6,213,973, titled “VASCULAR ACCESS PORT WITH ELONGATED SEPTUM” issued to Eliasen et al., dated Apr. 10, 2001; and U.S. Pat. No. 6,287,293, titled “METHOD AND APPARATUS FOR LOCATING THE INJECTION POINT OF AN IMPLANTED MEDICAL DEVICE” issued to Jones et al., dated Sep. 11, 2001, each of which is incorporated herein by reference in its entirety.
In certain circumstances, it may be desirable to reduce the priming volume of an access port to enhance the clearance of fluid (including medications) from the access port. The “priming volume” of an access port is defined herein as the volume of fluid contained within the port and port stem (and may include the fluid within an attached catheter). Reducing the priming volume may decrease the amount of fluid required to flush fluid from the access port, also referred to as clearing the access port. However, applicants have recognized that there is a tradeoff between the size and ease of use of the access catheter and the priming volume. In particular, an access port must be deep enough for the needle to penetrate the septum such that the opening in the needle tip is within the reservoir to allow fluid to pass into and out of the needle. Thus, most commonly available access ports are relatively large in size (e.g., have a large housing and fluid reservoir) so that they are easy to locate and inject into; however, as mentioned, the large size may contribute to a larger than optimal priming volume therein.
In certain circumstances, applicants have recognized that it can be desirable to provide access ports with geometries and configurations that assist in reducing the priming volume. Such access ports may be referred to herein as “fast clear ports.” Thus, described herein are fast clear ports, systems including fast clear ports, methods of using fast clear ports, and methods of manufacturing fast clear ports.